OpenCV imread(filename) fails in debug mode when u

Question

I have some C++ code and everything was working fine with OpenCV except the function imread(file). It was finding correctly the file and loading the name, but it wasn't loading any data.

Mat pattImage = imread(fileName, 0);

After some reaserch on the web I realized that I was in debug mode but with the release OpenCV libraries, instead of the debug ones.

debug library:    opencv_core231d.lib
release library:  opencv_core231.lib

Though it is the tipical stupid error I thought this shouldn't have anything to do, the debug libraries are supposed to allow OpenCV code debugging while the release libraries allow faster execution of the code, but I don't understand why imread was failing.

Can anybody explain me the differences between debug and release libraries in OpenCV and why this error occurs?

Is it an OpenCV bug?

Answer 1

Use FORWARD slash (/), instead of a backward slash (). Even in Windows!

Incorrect:

cv::imread("C:\example\1.jpg");

Correct:

cv::imread("C:/example/1.jpg");

Answer 2

I'll never get tired of telling people that the C++ OpenCV interface for Windows has the wierdest bugs.

Write a small test using the C interface to check if it works or not (cvLoadImage(), etc).

Update: now that you know that the C interface works properly, you can either go to the mailing list and report this bug there or dig into the code yourself to find why it fails.

Answer 3

In release mode you must use release libraries, in debug mode - debug libraries. It is no bug.

Answer 4

Had this problem using Qt (Qt Creator), linking the debug version of the respective library fixed it. This can be done automatically in the project configuration file (.pro):

QTCreator .pro file: Setting LIBS path depending on DEBUG / RELEASE